1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package dalvik.system; 18 19 /** 20 * Provides a limited interface to the Dalvik VM stack. This class is mostly 21 * used for implementing security checks. 22 * 23 * @hide 24 */ 25 public final class VMStack { 26 /** 27 * Returns the defining class loader of the caller's caller. 28 * 29 * @return the requested class loader, or {@code null} if this is the 30 * bootstrap class loader. 31 */ getCallingClassLoader()32 native public static ClassLoader getCallingClassLoader(); 33 34 /** 35 * Returns the class of the caller's caller's caller. 36 * 37 * @return the requested class, or {@code null}. 38 */ getStackClass2()39 native public static Class<?> getStackClass2(); 40 41 /** 42 * Creates an array of classes from the methods at the top of the stack. 43 * We continue until we reach the bottom of the stack or exceed the 44 * specified maximum depth. 45 * <p> 46 * The topmost stack frame (this method) and the one above that (the 47 * caller) are excluded from the array. Frames with java.lang.reflect 48 * classes are skipped over. 49 * <p> 50 * The classes in the array are the defining classes of the methods. 51 * <p> 52 * This is similar to Harmony's VMStack.getClasses, except that this 53 * implementation doesn't have a concept of "privileged" frames. 54 * 55 * @param maxDepth 56 * maximum number of classes to return, or -1 for all 57 * @return an array with classes for the most-recent methods on the stack 58 */ getClasses(int maxDepth)59 native public static Class<?>[] getClasses(int maxDepth); 60 61 /** 62 * Returns the first ClassLoader on the call stack that isn't either of 63 * the passed-in ClassLoaders. 64 */ getClosestUserClassLoader(ClassLoader bootstrap, ClassLoader system)65 public static ClassLoader getClosestUserClassLoader(ClassLoader bootstrap, 66 ClassLoader system) { 67 Class<?>[] stackClasses = VMStack.getClasses(-1); 68 for (Class<?> stackClass : stackClasses) { 69 ClassLoader loader = stackClass.getClassLoader(); 70 if (loader != null && loader != bootstrap && loader != system) { 71 return loader; 72 } 73 } 74 return null; 75 } 76 77 /** 78 * Retrieves the stack trace from the specified thread. 79 * 80 * @param t 81 * thread of interest 82 * @return an array of stack trace elements, or null if the thread 83 * doesn't have a stack trace (e.g. because it exited) 84 */ getThreadStackTrace(Thread t)85 native public static StackTraceElement[] getThreadStackTrace(Thread t); 86 87 /** 88 * Retrieves a partial stack trace from the specified thread into 89 * the provided array. 90 * 91 * @param t 92 * thread of interest 93 * @param stackTraceElements 94 * preallocated array for use when only the top of stack is 95 * desired. Unused elements will be filled with null values. 96 * @return the number of elements filled 97 */ fillStackTraceElements(Thread t, StackTraceElement[] stackTraceElements)98 native public static int fillStackTraceElements(Thread t, 99 StackTraceElement[] stackTraceElements); 100 } 101